1. Field of the Invention
The present invention relates to a process for producing a Langmuir-Blodgett (LB) film. More particularly, the present invention relates to a process for producing an LB film, which can produce an LB film using smaller equipment than the conventional production process and, at the same time, can easily produce an LB film formed of a plurality of dissimilar molecules.
2. Description of the Related Art
The Langmuir-Blodgett (LB) process has hitherto been widely used for the formation of organic ultrathin films. In the LB process, a thin film, formed on the surface of water, having a thickness corresponding to one molecule, that is, a monomolecular film, is developed under a certain surface pressure, and a solid substrate is moved up and down perpendicularly to the monomolecular film to transfer a condensed film in a close-packed state onto the substrate. The repetition of this procedure results in the build-up of an organic thin film on the substrate.
The conventional LB process has the problem that the surface pressure fluctuates, causing a fluctuation in the density or molecular orientation of the monomolecular film, so that the resultant organic thin film has a heterogeneous structure. In order to solve this problem, a film forming apparatus was proposed wherein, after the formation of a monomolecular film on the surface of water, the monomolecular film is compressed by a barrier to regulate the surface pressure (Japanese Unexamined Patent Publication (Kokai) No. 64-90058).
In the above conventional apparatus for producing an LB film, a monomolecular film is first developed on the surface of water and then compressed to form a condensed film. Therefore, the developing area before the compression had to be several tens of times as large as the area of the condensed film, unavoidably requiring a large apparatus. Further, the large developing area makes it difficult to maintain the orientation of the developed molecule. In addition, it causes an increased concern of impurities being included in the film.
Accordingly, an object of the present invention is to provide a process for producing an LB film, which can prevent the inclusion of impurities and produce an LB film using a small apparatus without using any large developing trough by dropping film forming molecules on the surface of water while compressing the resultant monomolecular film of a film forming molecule by taking advantage of a stream of a fluid to form a condensed film without developing the monomolecular film.